The present invention relates to the preparation of a new derivative of 8-(2-phenylethyl)-1-oxa-3,8-diazaspiro-(4.5) decan 2-one, by reaction of this compound, or an appropriate salt thereof, with 1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxopurine-7-acetic acid, or suitable derivative in the conditions stated hereinafter.
As reagent derivatives of the acid may be used its halides, preferably chloride and bromide, which result in good yields and are prepared, by means of known processes described in the scientific literature, by reaction of the acid with the corresponding phosphorus halides or thionyl halides. Acid anhydride is also used to carry out the reaction, which may be prepared "in situ", although the yield of the process may require recovery of the acid, which is formed as a secondary product at a ratio of one mol of acid to one mol of 1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxopurine-7-acetic anhydride, which is rather laborious.
As a medium is used an organic solvent or a mixture of two or more organic solvents which are inert in contrast to the reagents used, and which are selected among the terciary amines, preferably pyridine, trialkylamines and N-methyl morpholine, the aromatic hydrocarbons, preferably benzene, toluene and xylene, the halogenated carbons, preferably chloroform, dichloromethane, trichloroethane and dichloroethane, and the N,N-dialkylamides, preferably N,N-dimethyl formamide and N,N-dimethyl acetamide. Moisture must be avoided to the maximum, since it would affect negatively in the reaction, and this fact causes those solvents in which water is present to dry up, thereby reducing their content by physical and/or chemical means.
On the other hand, the temperature at which said reaction is carried out must be adequately controlled, which in no case should exceed 150.degree. C., since it would result in a form different from the desired one, and the quality of the product would be inferior to that obtained in operating between 50.degree. and 130.degree. C.
The reaction product may be isolated in the form of free base or in the form of an acceptable pharmaceutical salt, considering as such those of mineral acids, such as hydrocloric acid and sulfuric acid, and organic acids, such as acetic acid, 7-theophylline acid, lactic acid, oxalic acid, maleic acid and thenoic acid.
The 3-(1,2,3,6-tetrahydro-1,3-dimethyl-2,6-dioxopurine-7-acetyl)-8-(2-phenyl e thyl)-1-oxa-3,8-diazaspiro (4.5) decan-2-one and its acceptable pharmaceutical salts referred to by the present invention offer bronchodilatory activity, both "in vitro" and "in vivo", as well as anti-inflammatory activity, which make them potentially useful for their use as drugs.
The following examples are presented merely as an illustration and should not be interpreted as limiting the present invention, since many variants thereof are possible, without departing from the spirit and scope of the invention.